At the present the only agent generally available for visualization of the gall bladder and biliary tract by scinti-scanning is .sup.131 I-rose bengal. This agent suffers many disadvantages among these being high radiation dose to the patient, poor resolution due to poor counting statistics and high gamma energy.
The use of technetium-99m in a gall bladder localizing radio-pharmaceutical will nullify most of these disadvantages. Reports describing two .sup.99m Tc-compounds with this property have been published recently (in abstract form).
.sup.99M Tc-D-penicillamine has been reported to accumulate in the gall bladder of dogs and is apparently excreted via the liver. It is stated that the gall bladder is well visualized 120-180 minutes after injection and that preliminary studies in man have been carried out, requiring 3 hours for good gall bladder accumulation. (Krishnamurthy, G.T., Tubis, M., Endow, J.S. and Blahd, W.H., .sup.99m Tc-Penicillamine a new radio-pharmaceutical for cholescintigraphy. J. Nucl. Med. 13, 447 (1972). Further studies in humans have been reported more recently (Krishnamurthy, G.T., et al., .sup.99m Tc-Penicillamine cholescintigraphy: comparison with oral cholescystography. J. Nucl. Med. 14, 418 (1973).
This time interval is undesirably long for an agent in routine use. Another disadvantage is the possibility of reactions in sensitive individuals, which have been described in cases where D-Penicillamine has been used therapeutically, (Crawhall, J.C., Further observations on use of D-penicillamine in cystinuria. Brit. Med. J. 1, 1411 1964).
A.sup.99m Tc-labelled bile salt analogue has also been described. (Dugal, P., Eikman, E.A., Natarajan, T.K. and Wagner, H.N., Jr., A quantitative test of gall bladder function. J. Nucl. Med. 13, 428 (1972).
In dogs, this compound is said to accumulate rapidly within the liver and then move rapidly into the gall bladder. After a fatty meal, the gall bladder was observed to decrease in activity. In normal patients (Eikman, E.A., et al., Radioactive tracer techniques in the diagnosis of acute cholecystitis. J. Nucl. Med. 14, 393 (1973) radioactivity accumulates in the gall bladder allowing visualization within 90 minutes of injection of .sup.99m Tc-dihydrothioctic acid.
The objects of the present invention are to provide a more suitable diagnostic substance for gall bladder and biliary tract scanning.